NREL is a national laboratory of the U.S. Department of Energy

Office of Energy Efficiency & Renewable Energy

Operated by the Alliance for Sustainable Energy, LLC

This report is available at no cost from the National Renewable Energy

Laboratory (NREL) at www.nrel.gov/publications.

Contract No. DE-AC36-08GO28308

Optical and Durability 

Evaluation for Silvered 

Polymeric Mirrors and 

Reflectors

Cooperative Research and 

Development Final Report

CRADA Number: CRD-08-316

NREL Technical Contact: Matthew Gray

CRADA Report

NREL/TP-5500-62436

August 2014
NOTICE

The submitted manuscript has been offered by an employee of the Alliance for Sustainable Energy, LLC 

(Alliance), a contractor of the US Government under Contract No. DE-AC36-08GO28308. Accordingly, the US 

Government and Alliance retain a nonexclusive royalty-free license to publish or reproduce the published form of 

this contribution, or allow others to do so, for US Government purposes.

This report was prepared as an account of work sponsored by an agency of the United States government. 

Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, 

express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of 

any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately 

owned rights. Reference herein to any specific commercial product, process, or service by trade name, 

trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, 

or favoring by the United States government or any agency thereof. The views and opinions of authors 

expressed herein do not necessarily state or reflect those of the United States government or any agency thereof.

This report is available at no cost from the National Renewable Energy

Laboratory (NREL) at www.nrel.gov/publications.

Available electronically at http://www.osti.gov/scitech

Available for a processing fee to U.S. Department of Energy

and its contractors, in paper, from:

U.S. Department of Energy

Office of Scientific and Technical Information

P.O. Box 62

Oak Ridge, TN 37831-0062

phone: 865.576.8401

fax: 865.576.5728

email: mailto:reports@adonis.osti.gov

Available for sale to the public, in paper, from:

U.S. Department of Commerce

National Technical Information Service

5285 Port Royal Road

Springfield, VA 22161

phone: 800.553.6847

fax: 703.605.6900

email: orders@ntis.fedworld.gov

online ordering: http://www.ntis.gov/help/ordermethods.aspx

Cover Photos: (left to right) photo by Pat Corkery, NREL 16416, photo from SunEdison, NREL 17423, photo by Pat Corkery, NREL 

16560, photo by Dennis Schroeder, NREL 17613, photo by Dean Armstrong, NREL 17436, photo by Pat Corkery, NREL 17721.

NREL prints on paper that contains recycled content.
1

This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications.

Cooperative Research and Development Final Report

In accordance with Requirements set forth in Article XI.A(3) of the CRADA document, this document is 

the final CRADA report, including a list of Subject Inventions, to be forwarded to the Office of Science 

and Technical Information as part of the commitment to the public to demonstrate results of federally 

funded research.

CRADA Number: CRD-08-316

CRADA Title: Optical and Durability Evaluation for Silvered Polymeric Mirrors and Reflectors

Parties to the Agreement: 3M Company

Joint Work Statement Funding Table Showing DOE Commitment:

Estimated Costs NREL Shared Resources

Year 1 $ 150,000.00

Year 2 $ 00.00

Year 3 $ 00.00

TOTALS $ 150,000.00

Abstract of CRADA Work:

3M is currently developing silvered polymeric mirror reflectors as low-cost replacements for glass 

mirrors in concentrating solar power (CSP) systems. This effort is focused on development of reflectors 

comprising both metallized polymeric mirror films based on improved versions of ECP-305+ or other 

durable mirror film concepts and appropriate mechanically robust substrates. The objectives for this 

project are to reduce the system capital and operating costs and to lower the levelized cost of energy for 

CSP installations. The development of mirror reflectors involves work on both full reflectors and mirror 

films with and without coatings. Mirror reflectors must meet rigid optical specifications in terms of radius 

of curvature, slope errors and specularity. Mirror films must demonstrate long-term durability and 

maintain high reflectivity. 3M would like to augment internal capabilities to validate product performance 

with methods and tools developed at NREL to address these areas.

Summary of Research Results:

Primary work for this CRADA was carried out in accelerated weathering and periodic optical 

characterizations. 3M reflector materials were exposed on the Ultra-Accelerated Weathering System 

([UAWS] an R&D 100-winning technology developed in part by NREL) as well as in regular outdoor 

exposure (no acceleration) and ATLAS Ci-5000 Weatherometers (~8x acceleration. The UAWS has a 

concentration factor of 100x in the solar ultraviolet (UV) spectral region and, depending on cooperation 

of the weather, can achieve a 30-year equivalent exposure dose in the UV spectral region in ~1 – 1.5 

years. UV exposure and degradation is the most typical failure mode for film reflectors. Over the course 

of this CRADA we were able to show that the 3M reflector films could endure the 30 year life expected 

of CSP plants without significant degradation of overall reflectance or specularity. 3M has since made the 

reflector film that they were testing during this CRADA commercially available.
2

This report is available at no cost from the National Renewable Energy Laboratory (NREL) at www.nrel.gov/publications.

Subject Inventions Listing:

None

Report Date:

June 24, 2014

Responsible Technical Contact at Alliance/NREL:

Matthew Gray 

This document contains NO confidential, protectable, or proprietary information.